Monday, October 20, 2003

Climate change: a useful summary

This piece by Jack Hollander in the Wilson Quarterly provides a sane and useful summary of what is going on with climate change.

1. It is not true that there has been consistent warming for over a decade. 'From 1860 to 1940, Earth’s surface warmed about 0.4ºC. Then Earth’s surface cooled about 0.1ºC in the first four decades after 1940 and warmed about 0.3ºC in the next two. For those two most recent decades, temperature measurements of the atmosphere have also been available, and, while these measurements are subject to significant uncertainty, they indicate that the atmosphere’s temperature has remained essentially unchanged.'

2. The degree to which carbon dioxide etc added by human activity is to blame for warming is also not clear. The simple fact of there being more carbon dioxide in the atmosphere is not the same as demonstrating a man-made effect. Certainly, the fact that most of the extra CO2 was added at a time of cooling suggests at the very least that any effect is not necessarily dominant.

3. There is little justification for the idea of a stable climate, interfered with by humans. Climate change is the historical norm.

4. Most of the more alarming statements about climate change are based on the results of models which are known to be inaccurate and need further work. There are a number of factors which are not properly integrated into the analysis yet. "The forcings that drive long-term climate change," concludes James Hansen, one of the pioneers of climate change science, "are not known with an accuracy sufficient to define future climate change. Anthropogenic greenhouse gases, which are well measured, cause a strong positive forcing [warming]. But other, poorly measured, anthropogenic forcings, especially changes of atmospheric aerosols, clouds, and land-use patterns, cause a negative forcing that tends to offset greenhouse warming." Moreover, the models are incapable of predicting sudden changes, only gradual ones.

5. As a response to this, the Kyoto Protocols are deeply flawed. They don't include major developing countries, it takes no account of the cost of achieving carbon-reduction targets, and the cutbacks suggested would be both hugely expensive and ineffective.

6. Global temperature variation doesn't matter nearly as much as is suggested. 'During all of recorded history, humans have survived and prospered in climate zones far more different from one another than those that might result from the changes in global temperatures now being discussed.' Agriculture tends to do better in warmer rather than cooler periods; insect-borne disease is a problem of poverty, not temperature; sea-levels are always changing and adaptation has been possible, if not always without pain; there is no evidence of an increase in extreme weather events.

7. Even if everything the environmentalists say is true, 'It will be nearly impossible to slow climate warming appreciably without condemning much of the world to poverty, unless energy sources that emit little or no carbon dioxide become competitive with conventional fossil fuels.'